Radiation Therapy and Risk for Contralateral Breast Cancer

For many years, women with BRCA1/2 pathogenic germline mutations and breast cancer identified in one breast have made shared decisions with their surgeons to undergo bilateral mastectomy. More recently, some women elect to conserve the contralateral breast by undergoing radiation therapy (RT) to the affected breast and no intervention to the unaffected breast. This approach is supported by database and meta-analytic studies showing that breast-conserving therapy compared with mastectomy is associated with no differences in disease-free survival, local recurrence rate, breast cancer–specific survival, or overall survival. Still, a greater risk for contralateral breast cancer (CBC) has been reported in BRCA1/2 carriers with breast cancer diag…